In March 2014, Sisley's proposal to study marijuana use to treat post-traumatic stress disorder (PTSD) was approved by the National Institute on Drug Abuse.[1] After working at the University of Arizona for nearly eight years in various capacities, she was fired from the university in June 2014, ostensibly because of "funding and reorganization issues." Sisley, however, claims the firing was because of her interest in studying the potential medical uses of marijuana to treat PTSD.[2][3] Sisley has also claimed that the university failed to provide a location for the trial to take place, and that the University of Arizona was "fearful of the word 'marijuana' and [did] not want... their brand aligned with this research."[3] After she was terminated, the university released a statement saying that they had "not received political pressure to terminate any employee as has been suggested in some media and other reports."[3]

Sisley has also acknowledged that she is "not sold" on the efficacy of marijuana for this purpose, but she does think cannabis use to treat PTSD has shown enough promise to be studied in a controlled environment. Since being fired, Sisley's research has been supported by the Multidisciplinary Association for Psychedelic Studies, a California-based nonprofit organization, which intends to look for a new university where it can be conducted.[4] On July 28, 2014, the University of Arizona denied Sisley's appeal for reinstatement.[5] In April 2016, the Drug Enforcement Administration approved Sisley's study, which is aimed at determining whether marijuana is an effective treatment for PTSD.[6]